| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 993790 | TimDee | Railway (BOI17_railway) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
// I solved this problem in contest (it appeared on our TST2024), but i'm too lazy to code it again, so it's a copy of rainboy's submission.
#include <stdio.h>
#include <stdlib.h>
#define N 100000
int ij[N];
int *eh[N], eo[N];
void append(int i, int j) {
int o = eo[i]++;
if (o >= 2 && (o & o - 1) == 0)
eh[i] = (int *) realloc(eh[i], o * 2 * sizeof *eh[i]);
eh[i][o] = j;
}
int dd[N], pp[N], qq[N], ff[N], sz[N], ta[N], tb[N], qu[N], cnt;
void dfs(int p, int f, int i, int d) {
int o, j_;
qu[ta[i] = cnt++] = i;
dd[i] = d, pp[i] = p, ff[i] = f;
j_ = -1, sz[i] = 1;
for (o = 0; o < eo[i]; o++) {
int h = eh[i][o], j = i ^ ij[h];
if (h != f) {
dfs(i, h, j, d + 1);
if (j_ == -1 || sz[j_] < sz[j])
j_ = j;
sz[i] += sz[j];
}
}
if (j_ != -1)
qq[j_] = -1;
tb[i] = cnt;
}
int lca(int i, int j) {
while (qq[i] != qq[j])
if (dd[qq[i]] > dd[qq[j]])
i = pp[qq[i]];
else
j = pp[qq[j]];
return dd[i] < dd[j] ? i : j;
}
void sort(int *ii, int l, int r) {
while (l < r) {
int i = l, j = l, k = r, i_ = ii[l + rand_() % (r - l)], tmp;
while (j < k)
if (ta[ii[j]] == ta[i_])
j++;
else if (ta[ii[j]] < ta[i_]) {
tmp = ii[i], ii[i] = ii[j], ii[j] = tmp;
i++, j++;
} else {
k--;
tmp = ii[j], ii[j] = ii[k], ii[k] = tmp;
}
sort(ii, l, i);
l = k;
}
}
int main() {
static int kk[N];
static char used[N];
int n, m, k, h, i, j;
scanf("%d%d%d", &n, &m, &k);
for (i = 0; i < n; i++)
eh[i] = (int *) malloc(2 * sizeof *eh[i]);
for (h = 0; h < n - 1; h++) {
scanf("%d%d", &i, &j), i--, j--;
ij[h] = i ^ j;
append(i, h), append(j, h);
}
dfs(-1, -1, 0, 0);
for (h = 0; h < cnt; h++) {
i = qu[h];
qq[i] = qq[i] ? qq[pp[i]] : i;
}
while (m--) {
static int ii[N];
scanf("%d", &cnt);
for (h = 0; h < cnt; h++)
scanf("%d", &ii[h]), ii[h]--;
sort(ii, 0, cnt);
for (h = 0; h < cnt; h++) {
i = ii[h], j = lca(ii[h], ii[(h - 1 + cnt) % cnt]);
kk[ta[i]]++, kk[ta[j]]--;
}
}
for (i = 1; i < n; i++)
kk[i] += kk[i - 1];
cnt = 0;
for (i = 0; i < n; i++)
if (kk[tb[i] - 1] - (ta[i] == 0 ? 0 : kk[ta[i] - 1]) >= k)
used[ff[i]] = 1, cnt++;
printf("%d\n", cnt);
for (h = 0; h < n - 1; h++)
if (used[h])
printf("%d ", h + 1);
printf("\n");
return 0;
}